Classification

Stainless steels come in several types depending on their microstructure.

Austenitic stainless steels:

Contain at least 6 percent nickel and austenite—carbon-containing iron with a face-centered cubic structure—and have good corrosion resistance and high ductility (the ability of the material to bend without breaking). They are commonly used in food processing equipment, kitchen sinks, chemical plants, Kitchen furniture, etc.

Some of the different grades in austenitic stainless steel:

301

304

316L

321

310

Ferritic stainless steels:

(ferrite has a body-centered cubic structure) have better resistance to stress corrosion than austenitic, but they are difficult to weld. They are used in water coolers, hot water tanks, automobiles exhausts, etc.

Some of the different grades in ferritic stainless steel:

430

409

4003

403

Duplex stainless steels:

which generally contain equal amounts of ferrite and austenite, provide better resistance to pitting and crevice corrosion in most environments. They also have superior resistance to cracking due to chloride stress corrosion, and they are about twice as strong as the common austenitics. Therefore, duplex stainless steels are widely used in the chemical industry in refineries, gas-processing plants, pulp and paper plants, and sea water piping installations.

Some of the different grades in Duplex stainless steel:

2205

2304

2507

3RE60

329

Martensitic stainless steels

Contain iron having a needle-like structure. They are plain chromium steels containing between 12 and 18% chromium. Martensitic stainless steels are used in making shafts, surgical instruments, knife blades, spindles and pins.